1813221 has 24 divisors (see below), whose sum is σ = 2772224. Its totient is φ = 1140480.

The previous prime is 1813219. The next prime is 1813223. The reversal of 1813221 is 1223181.

It is an interprime number because it is at equal distance from previous prime (1813219) and next prime (1813223).

It is not a de Polignac number, because 1813221 - 2¹ = 1813219 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1813194 and 1813203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1813223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18645 + ... + 18741.

2^1813221 is an apocalyptic number.

It is an amenable number.

1813221 is a deficient number, since it is larger than the sum of its proper divisors (959003).

1813221 is a wasteful number, since it uses less digits than its factorization.

1813221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201 (or 198 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 1813221 is about 1346.5589478370. The cubic root of 1813221 is about 121.9411388549.

The spelling of 1813221 in words is "one million, eight hundred thirteen thousand, two hundred twenty-one".